Vol. 1, No. 3, August, 1962
MANGANESE PENTAC ARBONYL-FLUOROOLEFIN COMPLEXES 51 1 CONTRIBUTION FROM THE DEPARTMENT OF CHEMISTRY, HARVARD UNIVERSITY, CAMBRIDGE, MASSACHUSETTS
Chemistry of the Metal Carbonyls. XVH. Addition of Manganese Pentacarbonyl Hydride to Some FduorooleAns1B2 BY P. M. TKETCHEL,3 E. PITCHER, AND F. G. A. STONE
Received January 24, 1962 This paper describes the preparation and some chemical properties of the compoynds HCF2CF:Mn( CO)5, HCF2CFZCOMn(CO)S, HCFClCF%Mn(CO)S, HCCleCFtMn( CO)s, and CF&H=C( CFd)Mn(CO), The infrared and IBF and IH. n.m.r. spectra of the new manganese pentacarbonyl complexes are discussed,
We recently described a new class of compound wherein fluorocarbon groups are a-bonded to transition metals. These substances were obtained from reactions between metal carbonyls or certain of their derivatives and perfluoroalkyl iodides or tetrafluoroethylene ; or from reactions between sodium salts of metal carbonyls and perfluoroacyl or perfluoroallyl chloride^.^ We now have found that transition metal carbonyl hydrides add to certain unsaturated fluorocarbons to give stable compounds of this type. In this paper we report the addition of manganese pentacarbonyl hydride to tetrafluoroethylene, chlorotrifluoroethylene, l,l-dichloro-2,2-difluoroethylene, and hexafluoro-2-butyne. It has been reported previously5 that manganese pentacarbonyl hydride and ethylene do not react to give ethylmanganese pentacarbonyl, but form instead ethane and manganese carbonyl. Nevertheless, the recent work4 on fluorocarbon-transition metal complexes establishes that the group -CF2-M (M = transition metal) is formed easily, and suggests that reactions between transition metal hydrides and appropriate fluoroolefins might afford stable compounds, provided the hydride did not readily decompose before addition could take place. (1) Previous paper in this series, D. W McBride, S L Stafford, and F. G.A Stone, Iitorg Chem , 1, 386 (1962) (2) Presented in part at the 140th National Meeting of the Am Chem. Sac., Chicago, 1961, see P. M. Treichel, E. Pitcher, and F G. A Stone, Abstracts of Meeting, p 21-N. (3) National Science Foundation Predoctoral Fellow (4) (a) H D Kaesz, R B King, and F G A Stone, 2 S a t w foovsch., l a b , 763 (1960), (b) T A. Manuel, S L. Stefford, and F. G. A Stone, J A m Chem Soc , 83, 249 (1961); (c) R. B. King, 3! M Treichel, and F G A Stone, Pvoc Cham SOL.,69 (1961); (d) R B King, S L Stafford, P M Treichel, and F. G A. Stone, J . A m . Chem. SOL.,83,3604 (1961); (e) T. D Coyle, R . B. King, E Pitcher, S L. Stafford, P M Treichel, and F. G. A, Stone, J . Inorg. Nucl. Chem., 20, 172 (19611, (f) R B K h g , E. Pitcher, S L Stafford, P M Treichel, and F G.A Stone, “Advances in the Chemistry of the Coordination Compounds,” S Kirschner, ed , The Macmillan Co.,New York, N.Y., 1961, p. 619. (6) W. Hieber and G Wagner, Ann., 618, 24 (1958),
Exgerbental Fluorine n.m.r. spectra were recorded at 40 and 56.4 Mc. with a Varian V-4300B high resolution spectrometer equipped with a flux stabilizer. A precision audio oscillator and associated frequency counter were used for measurements of line separations. Line positions were determined by means of superposition, or are the average of a t least six calibrated traces. Proton n.m.r. spectra were recorded by means of a Varian A-60 spectrometer. The line positions were read from calibrated traces. Infrared spectra were recorded using a Perkin-Elmer Model 21 double-beam spectrophotometer. Manganese pentacarbonyl hydride was obtained by acidification of the salt NaMn( CO)b, prepared from sodium amalgam and manganese carbonyl in tetrahydrofuran .6 Tetrafluoroethylene was obtained by pyrolysis of Teflon resin a t 6OOQ.’ Hexafluoro-2-butyne was obtained by dechlorination of 2,3-dichloro-l,1,1,4,4,4-hexafluoro-2-butene.8 Other reagents were commercial samples. 1. Addition of Manganese Pentacarbonyl Hydride to Unsaturated Fluorocarbons. (a) Tetrafluoroethy1ene.A 150-ml. stainless steel Hoke bomb was attached to a high vacuum system, evacuated, and cooled to -196”. Pentane (20 ml.), manganese pentacarbonyl hydride (2.5 g., 12.8 mmoles), and tetrafluoroethylene (570 C C . , ~ 25.4 mmoles) were condensed into the bomb, which then was sealed and allowed to stand a t ambient temperatures for 22 hr. After venting the bomb in a hood, its liquid contents were poured into a flask. The bomb was rinsed several times with pentane and the washings added to the flask. The pentane solution was slowly evaporated (20 mm.), and the resulting residue transferred to a subliniation apparatus. Sublimation (25O,0.1 mm.) onto a 0’ probe gave 2.0 g. (69% yield based on HMn(CO)btaken) of white crystalline HCF&FSMn( CO)a (I) (Table I). Compound I was independently synthesized by the method previously described for preparing perfluoroalkylmanganese p e n t a c a r b ~ n y l s . ~The ~ acyl compound I1 (Table I ) was obtained (70% yield) as a white crystalline substance from the reaction between NaMn( CO), and (6) (a) W Hieber and G Wagner, Z iVaGuiforsch, 13b, 338 (19581, (b) R B King and F G A Stone, Inovg S y n , 7, in press (7) E E Lewis and M A Naylor, J A m Chew Soc , 69, 1968 (1947) ( 8 ) R N Haszeldine, J . Chem Soc , 2504 (1959) (9) Throughout this paper the: abbreviation “cc ” refers to gases at ktandard conditions,
512 P. M. TREICMEL, E. PITCHER, AND F. G. A . STONE
Inovganic Chemistry
TABLE I SOVIi 1?1 UORCK'ARBON I ) b R I V A l I V h b OP PIANCAC bbh,''
A1 P Compound
"C
I
Carbon, o/o Cdlcd. Found
Hydrogen, % Calcd Found
Fluorine, % ' Calcd Found
Manganese, Calcd. Found
nld wt Calcd.
Found
:30 5-31 5 98 4 28 ?I 0 0.41 26 6 25 4 18 6 18 I) Z9fi 297 46 5-47 0 29 G 29 0 31 .22 23 5 23.8 17 0 17 2 324 :149 43 0-44 0 26 9 27.0 32 .47 18 2 18 1 17 6 17 8 312 322 68 0-70 0 25 5 25 8 30 .24 11 5 10 1 16 7 16 3 329 328 Yellow 30 2 30 2 28 .53 31.8 31 9 15 4 15 6 358 355 liquid a Microanalyses were performed by Dr A. Bernhardt, Max Planck Institut fur Kohlenforschung, Mulheim, Germany, and by the Schwarzkopf Microanalytical Laboratories, Woodside, New York. * Isopiestic method C1, calcd. 11 4%; found, 11.27,.
JICF2CF2Mn(CO')5( I ) I~CF~CF~COMn(CO)S(II) HCFClCFJh( CO); ( III)c HCCltCF?Mn(CO)6(IV) C F C H :C( CF3)Mn(C0)s ( V )
HCFzCF2COCl in tetrahydrofuran. Pyrolysis of I1 a t 80" in vacuo for 18 hr. resulted in release of carbon monoxide and formation of I. (80% yield based on I1 taken.) (b) Chlorotrifluoroethy1ene.-Using a similar technique to that described above, manganese pentacarbonyl hydride (2.4 g., 12.3 mmoles) in 20 ml. of pentane was treated with chlorotrifluoroethylene (750 cc., 33.5 mmoles). The product (111) (1.9 g . , 49% yield based on manganese pentacarbonyl hydride taken) was a very volatile pale yellow solid (Table I). (c) 1,l-Dichloro-2,2-difluoroethylene.-From a reaction carried out in the Hoke bomb, IV (Table I) was isolated as pale yellow crystals (1.3 g., 39% yield) from manganese pentacarbonyl hydride (2.0 g., 10.2 mmoles) and l,l-dichloro-2,2-difluoroethylene(665 cc., 29.7 mmoles). (d) Hexafluoro-2-butyne .-From the reaction between manganese pentacarbonyl hydride (3.5 g., 17.8 mmoles) and hexafluoro-2-butyne (450 cc., 20 mmoles), under the conditions stated under ( a ) above, compound V (Table I ) was obtained (0.8 g., 12.5% yield) as a pale yellow liquid. 2. Reaction of I, 111, and 1V with Bromine.-In the hope of obtaining evidence for the structure of the organo group bonded to manganese, especially in the case of compounds arising from unsymmetrical olefins when two products of addition might occur, these compounds were treated with bromine t o cleave the organo group. Compound I (170.0 mg., 0.574 mmole) and a small glass tube containing bromine (1.0 g., 6.3 mmoles) were placed in a Pyrex reaction vessel of 300 ml. capacity. The reaction bulb was attached to the vacuum system, cooled, evacuated, and sealed. After heating for 14 hr. a t 120' the bulb was cooled to -196" and opened t o the vacuum system through an external trap containing an unsaturated hydrocarbon of low volatility, to absorb excess bromine. Fractionation of the volatile products gave 11.7 cc. (0.523 mmole, 91% of theory) of BrCFzCFt,H(identified by its infrared spectrumla) and 64 cc. (2.86 mmoles, 1007' of theory) of carbon monoxide.'l In a similar manner I11 (307.5 mg., 0.980 mmole) was treated with bromine (1.0 g., 6.3 mmoles) to give 10.3 cc. (0.46 mmole, 47% of theory) of BrCFtCFClII (identified (10) R. S. Haszeldine and B R Steele, J . Chem. Soc., 3747 (1954). (11) Here and in other experiments described in this paper involving formation of carbon monoxide, the latter was measured and identified by the method described previously (P. M. Treichel, E. Pitcher, R. B King, end F. G. A. Stone, J . A m . Chem. SOL.,83, 2593 (1961)).
by its infrared spectrumlo) and 108.4 cc. (4.90 mmoles, 99% of theory) of carbon monoxide. A sample (171.5 mg., 0.522 mmole) of IV on treatment with bromine (0.33 g., 2.1 mmoles) gave 3.1 cc. (0.138 mmole, 26% of theory) of BrCF&CltH (identified by its infrared spectrum12) and 58.6 cc. (2.6 mmoles, 100% of theory) of carbon monoxide. A less volatile liquid also was obtained which may have been a polybromoorganic compound, but it was not identified. 3. Pyrolysis of Compounds I and III.-A sample (654 mg., 2.21 mmoles) of I was placed in a 200-ml. Pyrex bulb, which then was evacuated, sealed off from the vacuum line, and heated for 18 hr. a t 120". On opening the bulb to the vacuum system the only observed product was a trace of non-condensable gas (carbon monoxide). Accordingly, the reaction vessel was resealed and heated a t 150' for 3 days. After this treatment a white solid was observed and on opening the bulb to the vacuum line 206 cc. (9.24 mmoles, 84% of theory) of carbon monoxide and 20.9 cc. of a mixture (identified by its infrared spectrum) of trifluoroethylene and 1,l-difluoroethylene were recovered. A 320.4-mg. (1.024 mmoles) sample of I11 was heated a t 80" for 16 hr. in a 200-ml. Pyrex bulb. After this treatment yellow and red solids were observed in the bulb. On opening the bulb, 48.2 cc. (2.15 mmoles, 427, of theory) of carbon monoxide and 17.4 cc. (0.778 mmole, 767' of theory) of trifluoroethylene (identified by its infrared spectrum) were recovered. The yellow and red solids remaining in the reaction vessel were separated and shown by their infrared spectral3 to be Mn(CO)6Cl and [Mn(CO)XlIz. 4. Reactions of Fluorocarbon-Transition Metal Compounds with Bases.I4 (a) HCF2CF2Mn(CO),.--,4 small tube containing a 213". (0.720 mmole) sample of I and 2 ml. of 20'30 sodium hydroxide solution was placed in a 250-ml. Pyrex bulb. This bulb then was attached to the vacuum line, evacuated, sealed off, and heated a t 90° for 1 hr. The bulb then was reattached to the vacuum system and opened, carbon monoxide (0.72 mmole, 20% of theory) being removed. The material remaining in the bulb, which included a ~7ellowsolid, was filtered. The filtrate was brought to a pH of 5 with acetic acid, carbon dioxide being released. The solution was treated with (12) J. R. Lacher, J. J. McKinley, C. Walden, K R Lea, and J D. Parks, J A m . Chem. Soc., 71, 1334 (1949). (13) E. W. Abel and G. Wilkinson, J. Chem. Soc., 1501 (19.59) (14) We are indebted to Dr. R. A. Plowman for helping with the experimental work described in this and the following section, and for making many valuable suggestions.
Vol. 1, No. 3, August, 1962
MANGANESE PENTACARBONYL-FLUOROOLEFIN COMPLEXES513
calrium chloride. A white precipitate formed which was allowed to settle for one day, then filtered, ignited, and weighed as calcium fluoride (100 mg., representing 89% of the fluorine content of the sample of I taken for reaction). As a check on the result, the calcium fluoride was converted to calcium sulfate (177.0 mg., implying 90% of the fluorine in the sample of I taken). The yellow solid produced by the base treatment proved to be insoluble in hydrocarbon solvents but soluble in acetone. On heating in air it explodes or burns. A 25.1mg. sample was analyzed for manganese by treating it cautiously with nitric acid, followed by evaporation. The residue was converted to the oxide Mnz08 by ignition in air a t 800" and weighed (12.1 mg., implying Mn = 33.5y0 in the original solid). As a check, the oxide was treated with sulfuric acid and sugar, evaporated, and heated to about 500" to form manganese(I1) sulfate (23.2 mg., implying Mn = 33.6% in the original solid). For a formulation [HC=CMn(C0)3], for the yellow solid, Mn calcd. = 33.5%. The infrared spectrum of the solid (Nujol and hexachlorobutadiene mulls , NaCl prism) showed bands a t 3610 (m), 2035 (s), 2015 (sh), 1958 (s), 1905 (s), 1600 (w, broad), 819 (m), 740 (m, broad), and 688 (m) cm.+. The band at 3610 em.-' was very sharp, and was assigned to the C-H stretch of a =C-H group.16 A number of experiments similar to the one described above were carried out. In one of these, a sample of I was heated a t 80"for 30 min. with 20% sodium hydroxide. After removal of carbon monoxide the contents of the reaction bulb were acidified with acetic acid (liberation of carbon dioxide observed) before filtration. The filtrate contained F- ion equivalent to 60% of the fluorine content of the sample of I taken for reaction. The yellow solid recovered was contaminated with NazSiFs (280 mg. = 32% of fluorine content of I). The yellow solid was removed from the fluorosilicate by washing with acetone. (b) ( C,Fi)2Fe(CO)r.-In order to determine whether strong base has a similar effect to that described above on fluoroalkyl derivatives of transition metals other than manganese, a 186.4-mg. (0.368 mmole) sample of bis(perfluoropropy1)-iron tetracarbonyl was treated with 20% sodium hydroxide (2 ml.) in a bulb for 2 hr. a t room temperature. A black solid formed. On opening the bulb no carbon monoxide was detected. Filtration, followed by washing the precipitate with acetone, led to the recovery of 48 nig. of starting material. The black solid afforded carbon dioxide on treattnent with acid, and was undoubtedly iron( 11) carbonate. Carbon dioxide was released on acidification of the filtrate, The latter then was analyzed for F - ion (see above). Found: CaF2, 140.8 mg.; F = 81% of the amount of (C3F~)zFe(C0)4 consumed. Reactions between bis-(perfluoroalky1)-iron tetracarbonyls and base a t elevated temperatures afforded carbon monoxide, carbon dioxide, and fluorocarbons (5-20o/,), as well a4 fluoride ion in solution. 5 . Reactions of Fluorocarbon-Transition Metal Compounds with Hydrogen Chloride. (a) HCF2CF2Mn(CO)s. -A 197.5-mg. (0.668 mmole) sample of I was heated a t 100" for 3 hr. with hydrogen chloride (86.5 cc.) in a Pyrex
bulb. A yellow solid appeared after 15 min., but subsequently disappeared. On opening the bulb to the vacuum line carbon monoxide (2.58 mmoles, 777, of theory) was removed. After treatment of the volatile components with triethylamine to remove excess hydrogen chloride, silicon tetrafluoride (6.9 cc., 46V0 of the fluorine content of the sample taken), identified by its infrared spectrum, was found as the only product. The solids in the bulb were extracted with cyclohexane, and, after filtering to remove the manganese( 11) chloride, the solvent was evaporated and the residue sublimed giving a small amount of manganese carbonyl. In other experiments it was observed that I and hydrogen chloride gas underwent little Or no reaction below about 70". At this temperature, however, trifluoroacetic acid and I afforded appreciable amounts of carbon monoxide and silicon tetrafluoride. (b) C2F6Mn(C0)6.-A 261.6-mg. (0.833 mmole) sample of perfluoroethylmanganese pentacarbonyl with hydrogen chloride gas (125.5 cc.) a t 110"for 30 min. yielded carbon monoxide (4.06 mmoles, 9770 of theory) and, after removal of the excess hydrogen chloride with triethylamine, silicon tetrafluoride (18.0 cc., 78% of the fluorine content of the CzFbMn(C0)s taken), identified by its infrared spectrum. (c) (C2Fs)zFe(CO)r.-A 208.3-mg. (0.514 mmole) sample of bis-(perfluoroethy1)-iron tetracarbonyl was observed not to react with hydrogen chloride gas (65.1 cc.) at room temperature over a period of 3 days. After heating (go", 15 min.) some decomposition was observed and carbon monoxide (0.723 mmole, 35% of theory)16 was obtained. After removal of excess hydrogen chloride with triethylamine, pentafluoroethane (2.4 cc., 10% of CzFa groups present), identified by its infrared spectrum, was found. Starting material still was observed to be present in the reaction vessel, and no silicon tetrafluoride had been formed. Accordingly, the Pyrex bulb was resealed with 55.5 cc. of hydrogen chloride and heated (100" 1 hr.), thereby affording carbon monoxide (1.19 mmoles, 58% of theory),16 and, after removal of hydrogen chloride with triethylamine, a mixture (11.9 cc.) of pentafluoroethane and silicon tetrafluoride. An examination of the infrared spectrum of this mixture suggested that its composition was approximately 30% C2F5H and 70% SiF4. 6 . Spectroscopic Studies.-The infrared absorptions of the various compounds are given in Table 11. I9F ant1 'H chemical shifts and spin coupling constants for conipounds I-IV are listed in Table 111, along with, for coiiiparison purposes, those of pentafluoroethane. The n .m .r. results for V are presented in Table 117, along with siinilar data for a cis-trans mixture of CF3C1C=CFCF3 studied in order to determine the structure of V.
(15) L. J. Bellamy, "The Infrared Spectra of Complex Molecules,'' 2nd Ed., Methuen, London, 1956.
(16) The carbon monoxide, by ignition over copper oxide at 800° (see ref. Il), was shown t o contain a trace (
